The present invention relates to an apparatus and method for ejecting sample well trays from a heating apparatus for biological samples. The apparatus improves the process of removing a sample well tray from a sample block after the cover of the heating apparatus is opened.
Biological testing has become an important tool in detecting and monitoring diseases. In the biological field, thermal cycling is utilized in order to perform polymerase chain reactions (PCR) and other reactions. To amplify DNA (Deoxyribose Nucleic Acid) using the PCR process, a specifically constituted liquid reaction mixture is cycled through a PCR protocol including several different temperature incubation periods. An aspect of the PCR process is the concept of thermal cycling: alternating steps of melting DNA, annealing short primers to the resulting single strands, and extending those primers to make new copies of double-stranded DNA. During thermal cycling, it is desirable that the temperature of each of a plurality of sample wells are substantially identical. In addition, it is important that condensation is avoided on the caps or other covering for the sample wells.
A common method of inhibiting condensation on the top of the sample wells is to provide a heated platen for pressing down on the tops or caps of the sample well trays. The platen is typically included as part of a cover and is typically metal. The platen transfers heat to the caps of the sample wells, thereby inhibiting condensation. In addition, the platen presses down on the sample wells so that the sample well outer conical surfaces are pressed firmly against the mating surfaces on the sample block. This increases heat transfer to the sample wells, and assists in providing a more uniform distribution of sample well temperatures. The platen also prevents thermal leakage from the interior of the device. Examples of a system with a platen and heated cover are described in U.S. Pat. Nos. 5,475,610, 5,602,756, and 5,710,381, all of which are assigned to the assignee of the present invention, and the contents of which are all hereby incorporated by reference herein.
The sample well trays can stick inside of the sample block due to expansion of the sample well trays and due to the force imparted on the trays by the thermal cycler cover. A considerable force may be required to unstick the sample wells and tray from the sample block and remove the tray. Unfortunately, laboratory robotic systems for removing sample well trays can sometimes have difficulty generating sufficient force to remove the sample well trays from the sample block. With the increase in the popularity of laboratory automation, it is particularly desirable to make the thermal cyclers more compatible to robotic removal of the sample well trays from the sample block. It is also desirable to increase the throughput of these devices.
Various aspects provide a thermal cycling device for biological samples. The thermal cycling device may include a sample block, an annular plate, and a plurality of spring devices interposed between the sample block and the annular plate. The sample block may have a plurality of openings for receiving sample wells of a sample well tray. The sample block may further have an upper surface positioned about the outer periphery of the sample block in a region outside of the openings in the sample block. The upper surface of the sample block defines a plurality of recesses. The annular plate may be positioned adjacent the outer periphery of the sample block and be configured to abut a bottom surface of the sample well tray when the sample well tray is positioned thereon. The plurality of spring device may be interposed between the sample block and the annular plate to urge the annular plate and sample well tray away from the sample block. The spring devices may be positioned at least partially within the plurality of recesses in the sample block.
Various aspects comprise a system for ejecting a sample well tray having a plurality of sample wells configured for containing biological material from a sample block of a thermal cycling device. The sample block can be configured to be engageable with a sample well tray and comprises a plurality of openings for receiving sample wells of a sample well tray therein. The urging mechanism may be interposed between the base and the sample tray to urge the sample tray away from the sample block. The urging mechanism may comprise an annular urging plate configured to engage a sample well tray, and a plurality of springs interposed between the sample block and the annular plate to urge the annular plate away from the sample block. The plurality of springs may be positioned at least partially within a plurality of recesses in the sample block. The urging mechanism may further be configured to eject the sample wells of the sample well tray from contacting the plurality of openings of the sample block automatically upon the opening of a cover of the thermal cycling device.
It is to be understood that both the foregoing general description and the following description of various embodiments are exemplary and explanatory only and are not restrictive.